Substituted flavanones

ABSTRACT

Substituted arylidene flavanones are provided which are useful as oxidation inhibitors for hydrocarbon compositions.

O Umted States Patent [151 3,678,044 Adams July 18, 1972 [54] SUBSTITUTED FLAVANONES [58] Field of Search ..260/240 F [72] Inventor: John Howard Adams, San Rafael, Calif. 56] References Cited h R h C S F [73] Asslgnee gsgf'tglafiftesearc ompany, an ran OTHER PUBLICATIONS [22] Filed: Oct. 22, 1970 Adams, J. Org. Chem, vol. 32, pages 3992- 8 (Dec. 1967). [2]] App]. No.: 83,209 Primary Examiner]ohn D. Randolph An me A. L. Snow, F. E. Johnston, G. F. Ma deb d Related US. Application Data i g urge f N 779,626, N 27, [63] lCsogstlnuatlon In part 0 Ser 0 ov [57] ABSTRACT Substituted arylidene flavanones are provided which are use- 52] US. Cl. ..260/240 F, l 1 7/132 R, 1 17/132 C, ful as oxidation inhibitors for hydrocarbon compositiona 260/41 C, 260/937, 260/345.2, 260/591 [51] Int. Cl. ..C07d 7/34 6 Claims, No Drawings SUBS'ITI'UTED FLAVANONFS CROSS-REFERENCE TO RELATED APPLlCATION This application is a continuation-in-part of copending US. application Ser. No. 779,626, filed Nov. 27, 1968.

BACKGROUND Hydrocarbons in general are subject to oxidation which may result in degradation of the hydrocarbon molecules. In particular, polymeric materials such as substantially crystalline poly-l-olefins, for example polypropylene, are subject to oxidative deterioration at the elevated temperatures normally employed in the manufacture and use of polymeric thermoplastic products from such materials.

Certain substituted chalcones and flavanones are effective when incorporated in hydrocarbons such as polypropylene to inhibit oxidative deterioration. Such chalcones and flavanones are disclosed in an article by Wittmann and Uragg published in 1965 in Monatsh. Chem, Vol. 96, page 381, which was referred to in Chemical Abstracts, Vol. 63, 69086 1965).

SUMMARY In accordance with the present invention, useful new substituted arylidene flavanones are provided having the formula:

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred substituted arylidene flavanones according to the present invention are those having branched chain alkyl groups such as isopropyl and tertiary butyl groups, particularly the latter in at least one of the R R R and R positions.

The substantially crystalline poly-l-olefms such as polypropylene containing the substituted chalcones and flavanones as employed in this invention may also contain additional oxidation inhibitors such as the dialkylthiodipropionates containing from one to 18 carbon atoms in the alkyl groups. Example include dimethylthiodipropionate, dilaurylthiodipropionate,

disteareodithiopropionate, and the like.

Substituted arylidene flavanones having the formula of the compounds of the invention and which were found to improve the oxidative stability of polypropylene include a large variety as shown by Table I:

Chalcone and flavanone precursors were prepared by the acid catalyzed condensation reaction between orthohydroxyacetophenone and a 4-hydroxy-3,5-dialkylbenzaldehyde.

Arylidene flavanones of the invention were prepared from the flavanone precursor by reaction with another mol of the same or a different 4-hydroxy-3,S-dialkylbenzaldehyde.

The following examples are given as illustrations of the substituted arylidene flavanones in accordance with the present invention. The proportions are on a weight basis unless otherwise specified.

Example 1 Preparation of 4-hydroxy-3,S-di-t-butylbenzaldehyde Boric acid 17.5 g.) and hexarnethylene tetrarnine (12.5 g.) were placed with 75 ml. of glycol in a 250 ml. Erlenmeyer flask equipped with magneu'c stirrer. At C. with rapid stirring, g. of 2,6-di-t-butylphenol was added gradually and the reaction continued for an additional 30 minutes. A 30 percent solution of sulfuric acid (75 ml.) was then added and the mixture allowed to cool. The white needles that formed on crystallization were filtered and recrystallized from methanol to yield 13.0 g. of 4-hydroxy-3,5-di-t-butylbenzaldehyde mp. 189C.

Other 4-hydroxy-3,S-dialkylbenzaldehydes were prepared by the same reaction. These are given in Table II.

HO -CHO Preparation of 3-(4-hydroxy-3,5-di't-butylbenzylidene)-4- hydroxy-3',5'-dimethylflavanone Compound R1 2 A solution of 270 mg. of 2,4-dihydroxy-3,S-dimethylchalcone and 230 mg. of 4-hydroxy-3,S-di-t-butylbenmldehyde in 50 ml. absolute ethanol saturated with dry hydrogen chloride l-b CH CH;, was stirred at 80C. for 1 hour and allowed to stand overnight. t CH3): 5 The product was precipitated by pouring the reaction mixture 1* C(C"a)a C(CH3)a into 300 ml. of ice water. It was then filtered, washed three times with water and dried to yield 475 mg. of 3-(4-hydroxy- 3,5-di-t-butylbenzylidene)-4'-hydroxy-3',5'-dimethyl- Exampleszand? flavanone. An infrared spectrum showed the characteristic Preparation of 2'4-dihydroxy-3,S-di-t-butylchalcone and 4- l cal'bonyl band 1,660 for an afl'lidene flavammehydroXy 35 di t butymavanone Other alkyl substituted arylidene flavanones were prepared A 00 1 round bottom fl k equipped with a stirrer, a by similar condensations. These are listed in Table V. thermometer, a gas inlet tube and a reflux condenser was I charged with 75 ml. of absolute ethanol. Then HCl gas was 1 5 IABLI" V bubbled through this alcohol for minutes. The resulting solution was cooled to room temperature at which time 0.68 Mkyl Subsmuted flavamms grams (5 m. moles) of orthohydroxy acetophenone and 1.17 R grams (5 m. moles) of 4-hydroxy-3,5-di-t-butylbenzaldehyde 1 was added. The reaction mixture was stirred for 2 hours and on was then poured into 50 ml. of ice water. This aqueous solu tion was extracted three times with 30 ml. portions of ether. 0 The ether extracts were washed with water, and then evaporated to about 10 ml. of volume. Pentane, 30 ml., was added to induce crystallization. The first crop of crystals, 0.35 grams, consisting of 3-(4-hydroxy-3,5-di-t-butylbenzylidene)- g CII 4-hydroxy-3',S-di-t-butylflavanone, were isolated by filtrao tion. Further concentration and cooling induced the precipitation of a second crop of crystals, weighing 0.6] grams, which were identified as 4-hydroxy-3,5-di-t-butylflavanone. Finally, 11 a third crop of crystals was obtained by further concentration. I This material weighed 0.35 grams and was identified as 2',4- lti dihydroxy-3,S-di-t-butylchalcone.

Other substituted chalcones and flavanones were prepared p/ound by a similar technique. Tables lll AND W list the compounds 4 -a H H --H --I[ prepared in this way along with their analytical properties. 44L

4-0. CH3 C(CI-I3); -CH; C(CH3): 'lAllLlC lll 4-d. CH(CH3)g CH(CH3)2 CH(OII1)2 CH(CII3)g 4-0 C(CH3)3 C(CH;); -C(CH;)1 -C(CH3): Substitutedcliiilconos 1H -CH3 -CH3 C(CH3)3 C(CH3);

l The alkyl substituted arylidene flavariones of this invention M have shown ability to enhance the resistance of substantially ll crystalline polypropylene to oxidative degradation caused by exposure to the atmosphere, especially at elevated temperatures. Accordingly, these compounds are mixed homogene- Analysis,

percent ously with such polypropylene at concentrations of at least C Y' ltl, Vl. p 8 d R1 R2 i l C H about 0.05 weight percent, usually about 0.05 to 0.50 weight percent, based on the polypropylene, to enhance the oxidative m"-.. H H 62 15 -9 ML 9 W2 76' 6.33 stabil ty of the polypropylene. This mixing may be achieved by 3. w (CH3)a 5 1564 77 18 91 blending the polymer and orgamc compound powders in con- CH CH1)! HCHWHB)? 18 74 ventional melt blenders. Minor amounts of other polymers z- 0011 CCH 2 i e a): 73-4 78 36 7 91 pigments, photostabilizers, other oxidation stabilizers, heat TABLE IV Substituted llavanones R1 0 l I 1 \C 2 Analysis, percent Yield, M.I)., A --A- Compound in it; lt C. (I ll ll ll 32 186-8 ClI-i 0H; 10 174.5-5. 6 76.12 6.10 -C l -C((J1l3) Insullicicnt for characterization (311(0113); ClI(Cll:) lnsumciont for characterization -0(CII -C(CH3)3 35 139-40 78.01 7. 03

Example 4 stabilizers, dye acceptors, dyes, fillers, and the like may also be incorporated into these mixtures.

The normally solid, substantially crystalline polypropylene which is stabilized by the compounds of this invention is a well known, commercial commodity. It is normally at least about As shown in Table VI, Example 5, unmodified 85 percent crystalline. It is essentially insoluble in refluxing polypropylene has essentially no stability to high temperature he tane oxidative conditions. The addition of 0.5% DLTDP, Example The compounds prepared as described in the above exam- 6, increases this stability to l5 days. Examples 7 through l ples were tested as oxidative stabilizers for polypropylene by then show the further increase in stability effected by adding the following procedure. 0.050 g. of dilaurylthiodipropionate 0.5 percent of various compounds of this invention. Oven lifes and 0.050 g. of the test compound (concentration A) were Of 20 to 40 days are obtained.

dissolved in acetone and poured into 10.0 g. of a commercial, f P l I compared to Example 5 Shows lhai the p ly r unstabilized polypropylene powder. The slurry wa i d stability 18 decreased by one-half upon decreasing the concenthoroughly until absolutely dry. The slurry was then mold l0 tration of DLTDP from 0.5 to 0.2 percent. However, upon adpressed at 475F. and up to 30,000 psi into a 20-mi1 h ding only 1 percent of the test compound of this invention This sheet was cut into 1.inch 2-inch were along concentration Of oven lifes Of t0 placed in an oven maintained at 138C. Other samples were y are Obtamed as shown y {Examples l prepared in the same way, except that only 0.010 g. of test and Exafnples f Included to how that no imcompound d 1020 f dilaur lthj di j were 15 provement in stability 15 obtained upon addition of unsubadded as the stabilizer combination (concentration B). All of sumted chalcones or flavanones- The corn unds of this invention are es eciall useful in stathe oven sam les were nodically examined by hand flexing Po P y to detemfinepthe time a: failure due to embritflement The bilizing polyolefin to metal catalyzed oxidatlve degradation, as cams are given in Table VL occurs in the presence of catalyst residues or when the 20 polyolefin is used as a metal coating. Table Vll contains comparative data showing that these compounds are superior to some currently used commercial oxidative stabilizers.

7 TABLE VII [Efiect of cltalconcs and flavanones on the stability of polypropylene containing metal impurities Oven lilc Example Test compound 2 at 138 0. number (example number) Type R1 R2 Metal ion 3 (days) 20 DLTDP only 0.1 21 2c (1110115000.. CHa C (CH3): 12.3 22 4f Flavanonc. CH3 CI-I g, 3 23 Commercial 1) 4 0. 3 24 DLTDP only Ti+++Al+++Na+.. 0.2 25 4e F1avanone -U(CH3): -C(CI-I3) Ti+++Al+++Na+. 7. 0 26 Commercial 1) 4 Ti+++Al+++Na+. 0. 3

1 All examples contain 0.2% dilaurylthiodipropionate.

2 Test compounds were added at the 0.1% concentration. I

Copper ion present at a concentration of 0.05%. Titanium, aluminum, and sodium 1011s present at a concentration of 0.29%, 0.16%, and 0.22%, respectively.

Commercial D is a 1,3-(3,5-di-tert.butyl-i-hydroxyphenoxy)-5-octylthiotr1aaine.

TABLE VI Effect of chalcones and flavanones on the oxidative stability of 40 Examples 20 and 24 show that DLTDP stabilized Pdypmpylene WW polypropylene in the presence of a metal ion has essentially OH R, the same life as polypropylene in the absence of any stabil- I izers. This indicates the rapid deterioration of a polyolefin -0H when in contact with metal ions. Examples 21, 22, and 25 l 0 show the lar e increase in stabilit resultin from addin 0.1

g y 8 g 0H percent of the compounds of this invention. Examples 23 and EL 2 26 illustrate the poor improvement with one typical commer- R cial prior art stabilizer. Other commercial materials or mixtures thereof, in contact with Cu, have oven lifes ranging g 0 E 3 from 0.1 to 16.0 days.

While the character of this invention has been described in 1 detail with numerous examples, this has been done by way of illustration onl and without limitation of the invention. It will Y I OH be apparent to those skilled in the art that modifications and variations of the illustrative examples may be made in the practice of the invention within the scope of the following OH claims.

Stabilizor (gggfin he Test coin ountl concena Ex. No. (l lxamplo number) tration 1 R1 Ra R: R4 (days) 3 5 Ul lmodlil ileil Nam 2.},

0.5 1) n o. ah 0 -or1. on. 33,0 -C (CH3): C(CHa)a' 31. 0 -C(CH3)3 -C (CHs)a 20. 7 s)s a)a 45.3 -'ii ii 9: 9 OH3 C(CH3)3 24. 0 -CH(CH3)2 CH(CHa)2 l8. 0 H H 8. 5 -OII3 --CH3 17. 5 CH3 CH3 -CH3 -CH3 29. 3 CII3 -C(CH3)3 -CH3 -C(CH3)3 30. 7 CH3 CH3 -C(CH:): -C(CH3); 28. 5

1 Stabilizer concentration A: 0.5% dilamylthiodiproptonate and 0.5% test compound. Stabilizer concentration B: 0.2% dilaurylthiodipropionate and 0.1% test compound.

2 Dilaurylthiodipropionate.

3 Average of two specimens.

I claim: 1. A compound of the formula wherein R,, R 1% and R are alkyl groups of from one to four carbon atoms each.

2. A compound of the formula of claim 1 having branched chain alkyl groups in at least one of the R R R and R positions.

3. A compound of claim 2 having isopropyl or tertiary butyl 5 groups in at least one of the R,, R R and R. positions.

4. A compound of claim 3 having tertiary butyl groups in at least one of the R R R and R positions.

5. A compound of claim 4 having tertiary butyl groups in each of the R R R and R positions.

6. A compound of claim 4 having methyl groups in each of the R and R positions and tertiary butyl groups in each of the R and R positions. 

2. A compound of the formula of claim 1 having branched chain alkyl groups in at least one of the R1, R2, R3, and R4 positions.
 3. A compound of claim 2 having isopropyl or tertiary butyl groups in at least one of the R1, R2, R3, and R4 positions.
 4. A compound of claim 3 having tertiary butyl groups in at least one of the R1, R2, R3, and R4 positions.
 5. A compound of claim 4 having tertiary butyl groups in each of the R1, R2, R3, and R4 positions.
 6. A compound of claim 4 having methyl groups in each of the R1 and R2 positions and tertiary butyl groups in each of the R3 and R4 positions. 